I cannot print but i have only the black cartridge...

Most modern printers use some colour when printing Black and therefore will not print if ANY ink cartridge is showing as empty.

Unless your printer has a setting for using Black ink only (this is not the same as printing a black and white document), then you will need to purchase and install the colour cartridges before printing can take place. The good thing about this is that very little colour ink is used when printing black and white documents - so they should last a long time.

Good luck.